1. Field of the Invention
The present invention relates to a polishing pad and a method for making the same, and more particularly, to a polishing pad having hollow structures and a method for making the same.
2. Description of the Related Art
FIG. 1 and FIG. 2 are schematic views of a method for making a conventional polishing pad. The method for making the conventional polishing pad is as follows. A resin 10 (usually a thermoplastic polyurethane polymeric foam) is infused into a mold cylinder, to form a bulk 11 after cooling and solidification. As shown in FIG. 1, the bulk 11 has a plurality of cells 12. Then, referring to FIG. 2, the bulk 11 is cut along a plurality of cutting lines 13 to form a plurality of polishing pads 14. The polishing pads 14 have independent bubble structures, and are usually used in high planarization polishing. However, the main problem of the polishing pads 14 lies in that, because the concentration distribution of the resin 10 in the mold cylinder is less uniform, during molding, the difference between temperature distributions in various positions of the mold cylinder may result in that the cells 12 have different sizes and distributions and the cells 12 are not easy to control. Thus, after a slicing process, the different sizes of the cells 12 on the slicing surfaces of the polishing pads 14 will become more obvious. During the grinding process, a grinding slurry permeates into large-aperture cells and small-aperture cells by different degrees, which will cause nonuniform grinding and deposition of the grinding slurry, thus easily producing grinding defects.
Therefore, it is necessary to provide an innovative and progressive polishing pad and a method for making the same, so as to solve the above problems.